Likely be loose belt. If not give your self 10 mins to tesnion belt or an hour and with a basic tool kit to change the alternator and you will have it sorted.
To tension belt need a 13mm spanner,13mm socket and 10 mm spanner or socket
I forgot what the bottom mount nut size is but it's something between 13-16mm iirc.
Before people start going on about how it should only take 20mins etc etc I am assuming that vtr02 is quite new to the mechanical side of things.